The present invention relates to an energy collecting system and a method of operating the same in which energy is collected through generation of electric power by a waterwheel using water used by, for example, an air-conditioning load or the like in a building.
For example, as an air-conditioning system in a building, there has been widely employed an air-conditioning system of heat storage type in which a heat source is operated using inexpensive nighttime electric power to store generated heat in a heat storage. In the daytime in which air-conditioning load takes place, the stored heat is fed from the heat storage to the load, i.e., an air conditioner to achieve air-conditioning operation.
FIG. 12 is a diagram showing a configuration of an example of the prior art, namely, an open-loop air-conditioning system of heat storage type. In a primary-side system S1, the configuration includes a water pump 1 which feeds water from a heat storage 16 to supply the water via a water supply pipe 4a to a heat source 4 and a both-end motor 2 of which one shaft end is directly coupled with the water pump using a shaft coupling to drive the water pump. The other shaft end is coupled with a waterwheel 12 via a clutch 12b. The waterwheel is disposed at a position at which potential energy of water discharged from the heat source can be completely collected. Numerals 18 and 19 indicate electric power sources, numeral 5 is a two-way valve to adjust a quantity of heat generated by the heat source, numeral 6a is a water supply pipe connecting the heat source to the waterwheel, and numeral 6 is an expansion tank associated with the water supply pipe. The tank 6 breaks a siphon to apply a head of the supplied water (potential energy thereof) to the waterwheel. In place of the expansion tank, a vacuum breaking valve may be disposed depending on cases. Numeral 12c indicates a water supply pipe to return the water from the waterwheel to the heat storage. That is, the water supplied to the heat source 4 by the water pump 1 is heated by the heat source and is then fed to the waterwheel 12. The waterwheel 12 is operated by the potential energy of the water to generate power and then imparts the power to the both-end motor 2. The load of the motor becomes lower than that of the water pump, the discrepancy therebetween corresponds to the power imparted from the waterwheel. The water from the waterwheel then returns to the heat storage.
The secondary-side system S2 is a load of an air conditioner or the like and supplies water from the heat storage 16 via a water supply pipe 7a to an air han (air handling unit) 8 and a fan coil 9 by a pump 7. The air han 8 includes an adjusting valve 8a to adjust a quantity of heat. The fan coil 9 also includes a similar adjusting valve 9a. The water of which heat is radiated is returned via the water supply pipe 7b to the heat storage 16.
FIG. 13 shows an operating characteristic graph of a pump and a waterwheel in an example of the prior art. A total water pumping-up process of the pump, an effective head of the waterwheel, and power of the pump and the waterwheel are indicated along an ordinate. A water flow rate is indicated along an abscissa. A curve A is a curve of Q,H performance of the pump and a curve C is a curve of shaft power when the waterwheel is not operated. The total water pumping-up process is required to operate only the water pump to supply water at a flow rate of Q0 to the water supply system shown in FIG. 9. The operation point in this operation is point O4 on the curve A. Power consumed in this operation is L1 indicated by pump shaft power, and the operation point is point O1 on the curve C. A curve B indicates an effective head of the waterwheel (pressure head difference between the inlet and the outlet of the waterwheel). This means that when water flows at a flow rate of Q0, a pressure head difference (effective head) of H1 occurs between the inlet and the outlet of the waterwheel, and this potential energy is absorbed to generate power as below.
A curve D is a power curve when the water pump and the waterwheel are operated. Power consumed in the operation is L2 indicated by pump shaft power and the operation point is point O2 on the curve D. That is, when the flow rate is Q0, power generated by the waterwheel is L3.
In this case, the power collection ratio (L3/L1) is about 20% to about 30%.
In this way, the conventional apparatus effectively uses potential energy of the pumped-up water passed through the heat source.
For example, JP-A-50-128801 (a power collection pumping machine) and JP-A-50-49701 (a power collection pumping machine) describes known examples of this apparatus. However, the prior art technique uses a clutch to directly couple a motor with a waterwheel and there is a problem of improvement of transfer efficiency of the clutch. There exists another problem. That is, the energy collected by the waterwheel is power and there is a problem that the power cannot be used in this case, in consideration of structure, for any other load in the building. JP-A-5-10245 (an electric power generator using waterwheel of paddle-wheel type) is a known example of waterwheel electric power generation using a waterwheel in a dam, a paddy field, or a watercourse.
It is therefore an object of the present invention to collect unused energy in a building by waterwheel electric power generation to use the energy again.
According to the present invention, there is provided an energy collecting system comprising as basic units a heat storage disposed in a lower section of a building; a heat source disposed in an upper section of the building for imparting heat to water supplied from the heat storage by electric power from a commercial power source and thereby producing cool or warm water; a primary cool/warm water pump for pumping up the water from the heat storage and supplying the water via a sucking pipe to the heat source; a water supply pipe disposed between a discharge outlet of the primary cool/warm water pump and the heat source; a water supply pipe for returning water from a discharge outlet of the heat source to the heat storage; an expansion tank or a vacuum breaking valve disposed in a highest section of the water supply pipe; a waterwheel disposed in a lowest section of the water supply pipe for collecting potential energy of the water discharged from the heat source; an electric power generator rotated by torque generated by the waterwheel to generate electric power; an inverter connected to an output port of the electric power generator for converting a voltage and a frequency of electric power generated by the electric power generator into a desired voltage and a desired frequency; a system collaboration unit between the motor and a commercial power source for changing a system from the power source to a side of the motor or from the inverter to a side of the commercial power source; and a cable for connecting an electric path between the system collaboration unit and the motor to an output port of the inverter.
To Start Operation
1) Before operation, close a waterwheel inlet valve, a waterwheel outlet valve, and a waterwheel bypass valve. First, turn on power of the heat source and power of the motor to drive the primary cool/warm pump.
2) Next, transmit an operation request signal from the heat source side to the primary cool/warm pump.
3) The primary cool/warm pump receives the operation request signal transmitted from the heat source side to start its operation and supply wager from the heat storage to the load side. Simultaneously, the pump transmits an operation answer signal to the heat source.
4) After the operation answer signal is received, when a predetermined period of time lapses enough to guarantee a water supply pressure, the heat source starts its operation.
5) When a predetermined period of time lapses after the heat source starts its operation, the waterwheel outlet and inlet valves are opened. In association therewith, the waterwheel starts its operation. The rotation speed of the waterwheel increases with a lapse of time and the electric power generator starts its operation.
6) Generated power is supplied via the inverter to a load, for example, the motor to drive the primary cool/warm pump. In another embodiment, the system collaboration unit is connected to a commercial power source and there is provided a unit to connect an output from the inverter to an electric path between the system collaboration unit and a load. In this case, when the load is in a low state and the generated power is excessive, unused power is fed back via the system collaboration unit to the power source.
7) The expansion tank or the vacuum breaking valve is disposed in an upper section of the water supply pipe and includes an atmospheric opening or a function similar to that of the atmospheric opening. The tank or the valve prevents expansion of water in the water supply pipe and breaks a vacuum state by exhausting air from the pipe or by sucking external air therein to help the supplied water fall onto the waterwheel.
In another embodiment, a pressure sensor disposed in the vicinity of the waterwheel senses pressure at the position. When the water pressure becomes equal to or more than a predetermined value, an automatic valve disposed in the vicinity of the waterwheel is opened.
To Stop Operation
8) When a predetermined period of time lapses after the heat source starts its operation, close the waterwheel outlet valve and stop the waterwheel. Stop the electric power generator.
9) Stop supplying the generated power, stop the inverter, stop supplying power to the motor to drive the primary cool/warm pump.
10) Transmit a stop request signal from the heat source side to the primary cool/warm pump side.
11) Receive the stop request signal, stop the motor to drive the primary cool/warm pump, and return a stop answer signal to the heat source.
12) Interrupt the power to the motor to drive the primary cool/warm pump and interrupt the power to the heat source.
According to the present invention, there is provided an energy collecting system in a building, wherein a water pump on a secondary-side system to supply water to a group of air-conditioning loads is driven by an inverter, a waterwheel is operated by potential energy of water used by the air-conditioning loads, an electric power generator is operated by torque generated by the waterwheel, power generated by the electric power generator is converted by a regenerative converter into direct-current (dc) power, and positive-side dc power P thereof and negative-side dc power N thereof are outputted to dc terminals P and N of an inverter for the water pump.
The system of the present invention is configured as above and operates as follows.
1) Before operation, the waterwheel inlet and outlet valves and the waterwheel bypass valve are closed. First, the inverter to drive the water pump in the secondary-side system is activated to operate the water pump to supply water to air conditioners as air-conditioning loads. The inverter receives a sense signal from a pressure sensor disposed on the pump discharge side to conduct, for example, control operation to fix a terminal pressure.
2) The waterwheel starts its operation when the water having passed the respective air conditioners flows thereonto. The electric power generator starts its operation by torque generated by the waterwheel to generate electric power.
3) The inverter on the electric power generator side converts power (alternating current) generated by the electric power generator into dc power to supply the dc power to another inverter via a cable.
The present invention is not limited to a system or a facility arranged in a building. That is, the configuration includes a heat storage for storing water fed from a heat source, a heat source for producing cool or warm water using water supplied from the heat storage, a pump for supplying the water from the heat storage to the heat source, a motor for driving the pump, a waterwheel rotated by the water supplied from the heat source, an electric power generator driven by the waterwheel for generating electric power, an inverter connected to an output port of the electric power generator, a system collaboration unit disposed between the motor and a commercial power source for conducting a change-over operation between a system connecting the commercial power source to the motor and a system connecting the inverter to the commercial power source, and a connecting line for connecting an electric path between the system collaboration unit and the motor to an output port of the inverter.
Other objects, features and advantages of the invention will become apparent from the following description of the embodiments of the invention taken in conjunction with the accompanying drawings.